Here's an inside look at how M&M's are made

Most of us know (and love) M&M’s — those tiny, colourful chocolates that “melt in your mouth, not in your hand.”

But very few of us are familiar with the process of how they’re made.

Lucky for you, Business Insider recently visited the Mars Chocolate North America campus in Hackettstown, New Jersey, where 50% of all M&M’s sold in the US are made.

Mars Chocolate — a segment of the $33 billion Mars candy, pet care, and beverage company — is the producer of M&M’s, along with 10 other billion-dollar brands including Snickers, Dove, Milky Way, and Twix.

The Mars Chocolate North America campus, which opened in 1958 and employs 1,200 people, is home to a corporate office as well as the M&M’s factory.

While touring the campus, we learned that the M&M’s brand was founded by Forrest E. Mars, Sr. in 1941, and that it was the first candy in space in 1982.

Leighanne Eide, the Mars Chocolate North America site director, walked us through the factory and explained each step of the process. We were restricted from taking photos of certain top-secret areas — but below you’ll get a better idea of how the M&M’s-making process works:

The smell of sweet chocolate hit us as we approached the factory, which is a few hundred yards from the Mars Chocolate office in Hackettstown, New Jersey.

Courtney Verrill

Upon entering the factory, we were asked to remove all jewellery. Next, Eide examined our fingernails to see if we were wearing nail polish. (They don't want chipped nail polish getting mixed in with the product.) Mine were polished, so I was asked to wear gloves. We were also required to wear a Mars-branded lab coat, like all factory associates.

Courtney Verrill

Next we were given hard hats, safety glasses, ear plugs, and hair nets.

Courtney Verrill

Everyone who enters the factory is required to wear this gear.

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Before heading in, we were asked to wash our hands (even if we were wearing gloves for the tour).

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The tour finally begins! We start by walking down this colourful hallway lined with lively paintings of M&M's characters.

Courtney Verrill

The Hackettstown plant creates M&M's Milk Chocolate, M&M's Minis, and Peanut M&M's, as well as 21 different colours and custom print products.

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'Mixing and tempering the chocolate are key,' Eide explains. 'Conching' is the first part of the process, when all of the raw material for chocolate is mixed together.

Courtney Verrill

The chocolate is then sent to standardising. where it is tempered to the correct temperature needed to create the desired shape of M&M's.

Courtney Verrill

Next, the chocolates are sent through the cooling tunnels to ensure they are cooled and ready for the colouring process.

Courtney Verrill

Eide let us try the M&M's chocolates at every stage in the process. 'Fresh' and 'sweet' don't even begin to describe how they tasted.

Courtney Verrill

Once the chocolates are cooled, they are given their signature colours -- a process that can't be rushed.

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The colouring drips slowly until the pieces are vibrant.

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The signature colours are yellow, red, green, brown, orange, and blue, the newest colour. Blue was introduced in 1995 after consumers voted on a colour to replace the tan M&M's, which had been around since the late 1940s.

Courtney Verrill

For Peanut M&M's, the nuts -- which are mainly supplied to Hackettstown from the Southeast region of the US -- go through a roasting process. Then they are sprayed with chocolate three times to get the right chocolate-to-nut ratio.

Courtney Verrill

'Millions of M&M's are made here each day,' Eide says. The factory, which is approximately 460,000 square feet, is very loud and sweet-smelling. 'The odor gets into your clothes, and it might be pleasant now, but once you get home it smells more like spoiled milk,' one associate explains.

Courtney Verrill

A lot of the process is proprietary and we were not allowed to see -- or photograph -- certain areas of the factory. 'Everyone always wants to know how we place the 'M' on each M&M, but that's still top secret,' Eide explains. 'For such a small piece of chocolate, M&M's are surprisingly sophisticated. We can't share all of the details behind the production process because we want to keep the magic and mystery behind the 'M' alive.'

Courtney Verrill

But once that step is done, the pieces are packaged and sent across the country.

Courtney Verrill

'M&M's today taste the same as they did when the first M&M's were produced in 1941 and that's a direct result of our extreme focus on delivering consistent, outstanding quality,' Eide says.

Courtney Verrill

From start to finish, she says, it takes anywhere from 10 to 12 hours to create a bag of M&M's.